Integrated circuit manufacturers use inspection systems to detect anomalies, such as defects, in substrates. Generally, an inspection system rasters the surface of the substrate with one or more optical sensors, and generates image data based on the images detected by the sensors. This image data is analyzed according to one or more of a variety of different algorithms to determine where defects might exist on the substrate. Integrated circuit manufacturers demand that such inspection systems meet several criteria. Among these criteria is that the inspection system must be extremely accurate, fast, and reliable. Further, such inspection systems should preferably be reasonably priced and relatively flexible.
Prior art inspection systems have implemented one or both of pipelined systems or computers that are networked in a switched fabric topology, which use highly customized hardware. Customized hardware has several disadvantages as compared to commercially available hardware, including higher nonrecurring engineering costs for the developer, lower reliability, longer development times, and more inflexibility in changing algorithms. Switched fabric systems have additional disadvantages, including high cost, lack of standards between manufacturers, and development lag in the components, such as the level of microprocessor that is built into such systems.
Commercial hardware, by contrast, tends to be more reliable, more versatile, and less expensive. For example, large computer manufacturers devote a tremendous amount of engineering effort to ensure that the latest technologies are implemented in their products, and that those products are brought to market as soon as possible. This large engineering effort is then factored into the price of the many, many units that they anticipate selling. Thus, the large development costs are spread quite thin as to each unit that is purchased. The development costs for customized hardware, on the other hand, must be borne on a relatively very small number of units.
Further, once a commercial product is developed, the engineering support team continually updates, improves, and bug fixes that product. Again, these costs are distributed over all of the many units that are sold by a large manufacturer. Again, the expenses of such efforts for customized hardware must be borne by a very few units. Often, the number of units makes such levels of support for customized hardware financially unreasonable to offer or to buy. Thus, prior art inspection systems, while perhaps having acceptable speed and accuracy, have been woefully lacking in the categories of flexibility, reliability, and cost.
What is needed, therefore, is a system that overcomes problems such as those described above, at least in part.